A chemical amplification resist composition is a pattern forming material of forming a pattern on a substrate by producing an acid in the exposed part upon irradiation of radiation such as far ultraviolet light, and changing the solubility in a developer between the part irradiated with actinic radiation and the non-irradiated part resulting from a reaction using the generated acid as a catalyst.
In the case of using a KrF excimer laser as the exposure light source, a good pattern with high sensitivity and high resolution is formed because a resin exhibiting small absorption mainly in the 248-nm region and having poly(hydroxystyrene) as the basic skeleton is used as the main component, and this is a good system as compared with the conventional naphthoquinone diazide/novolak resin system.
On the other hand, in the case where a light source at a shorter wavelength, for example, an AfF excimer laser (193 nm) is used as the exposure light source, the above-described chemical amplification system is insufficient because the compound having an aromatic group inherently exhibits large absorption in the 193-nm region.
Therefore, development of a resist for an ArF excimer laser, containing a resin having an alicyclic hydrocarbon structure, is proceeding.
It is known that the resin having an alicyclic hydrocarbon structure, which is used in the resist for an ArF excimer laser, generally has high hydrophobicity and poor affinity for a developer. When the affinity for a developer is poor, the development does not proceed uniformly and this may adversely affect the dimensional uniformity of pattern or may give rise to a development defect. As for the measures to solve this problem, JP-A-2001-215704 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses that a resin having a certain high-polarity polymerization unit is effective for the improvement of wettability to an alkali developer. However, even such measures cannot be said to have a satisfactory performance with respect to the mask error factor (hereinafter referred to as “MEF”) which is one of the image performances. The MEF indicates a phenomenon that the fluctuation in the mask precision is magnified by the resist.